Process for production of water-soluble vegetable fibers, biodegradable film, paste, chewing gum and low calorie food products

ABSTRACT

There is disclosed a process for production of water-soluble vegetable fibers in a high yield with minimizing contamination of protein or amino acids resulting from degradation of protein by degrading water-insoluble vegetable fibers containing protein under acidic conditions of at about the isoelectric point of the protein and at a temperature of 130° C. or lower. Biodegradable films, paste, chewing gum and low calorie food products using the water-soluble vegetable fibers are also disclosed.

[0001] This application is a divisional of Ser. No. 09/389,623, filedSep. 3, 1999, which is a divisional of Ser. No. 08/714,957, filed Sep.17, 1996 (now U.S. Pat. No. 6,004,616), which is a divisional of Ser.No. 08/437,983, filed May 10, 1995 (now U.S. Pat. No. 5,587,197), whichis a continuation-in-part of Ser. No. 08/076,946, filed Jun. 16, 1993,now abandoned, which is a continuation of Ser. No. 07/768,412, filedOct. 7, 1991, now abandoned, which is a §371 application ofPCT/JP91/00132, filed Feb. 5, 1991.

FIELD OF THE INVENTION

[0002] The present invention relates to a process for production ofwater-soluble vegetable fibers from water-insoluble vegetable fiberswhich are residues obtained by defatting oil seeds such as soybeans andthe like, and extracting protein therefrom (e.g., “okara” and the like),or residues obtained by extracting starch from cereals. Further, thepresent invention relates to transparent biodegradable films, paste andchewing gum as well as low calorie food products using the water solublevegetable fibers.

PRIOR ART

[0003] Residues obtained by extracting fats and oils from oil seeds andthen extracting protein, or by extracting starch from cereals are richin vegetable fibers. However, it is difficult to recover the vegetablefibers in good yield because remaining protein entangles with vegetablefibers. Further, because of water-insolubility of these vegetablefibers, it is difficult to obtain water-soluble vegetable fibers in goodyield with minimizing contamination of protein by degrading thesewater-insoluble vegetable fibers. For example, a residue, “okara”, whichis obtained by extracting fats and oils as well as protein from soybeansand the like are water-insoluble vegetable fibers still containingsoybean protein. When the water-insoluble vegetable fibers are degradedwith an alkali to extract water-soluble polysaccharides, the saccharidesare degraded to oligosaccharides, or soybean protein, degraded soybeanpeptide and/or amino acids are contaminated. Thus, it is difficult toobtain highly purified vegetable fibers in a high yield.

[0004] At present, no process for recovering water-soluble vegetablefibers in high purity and high yield from such water-insoluble fibershas been found. If it were possible to obtain water-soluble vegetablefibers in high purity and high yield, such water-soluble vegetablefibers could be widely applied to various kinds of films and adhesives,food products and the like. For example, plastic package films are notnaturally degraded. Although collagen films and pullulan films havebiodegradable properties, i.e., capability for degradation bymicroorganisms, and the like, there are problems that collagen filmshave inferior heat-seal property, and pullulan films are expensive. Onthe other hand, it is possible to obtain the films without theseproblems by using the water-soluble vegetable fibers.

[0005] Further, adhesives such as animal glue, modified starch, gumarabic, pullulan, polyvinyl alcohol and the like, in particular, pasteas remoistening adhesives have practical problems that their adhesivestrength is low, they are expensive, and the like. However, suchproblems can be solved by using the water-soluble vegetable fibers.

[0006] Further, for example, when pullulan, which is water solublepolysaccharide produced by a microorganism, is used in chewing gum,pullulan is expensive in comparison with the water-soluble vegetablefibers, and the resulting chewing gum has inferior durability ofpleasant chewing property and inferior water retention. However, whenthe water-soluble vegetable fibers is used, such problems can be solved.

[0007] Furthermore, the water-soluble vegetable fibers can be used forlow calorie food products and such low calorie food products have notbeen known heretofore in the prior art.

OBJECTS OF THE INVENTION

[0008] The object of the present invention is to provide a process forproduction of water-soluble vegetable fibers from water-insolublevegetable fibers containing protein, and is to provide films, paste,chewing gum and low calorie food products obtained by using theresulting water-soluble vegetable fibers.

DISCLOSURE OF THE INVENTION

[0009] The process for production of water-soluble vegetable fibers ofthe present invention comprises degrading water-insoluble vegetablefibers containing protein under acidic conditions of at about theisoelectric point of the protein and at a temperature of 130° C. orlower.

[0010] As the water-insoluble vegetable fibers containing protein, therecan be used residues obtained by removing husks, fats and oils andprotein from oil seeds (e.g., soybeans, palm, coconut, corn, cottonseed,corn, etc.), and residues obtained by removing grounds, starch and thelike from cereals (e.g., rice, wheat, etc.).

[0011] In the process of the present invention, it is suitable todegrade the water-insoluble vegetable fibers by heating at about anisoelectric point (normally, acidic range) of protein which is containedin the water insoluble vegetable fibers. Thereby, in comparison withalkaline degradation, contamination of protein in a degraded fractioncan be minimized and no post step for removing protein is required toobtain water soluble-vegetable fibers having lower protein contents andhigh purity. Further, formation of any harmful material such aslysinoalanine or the like can be prevented and this is preferred fromthe viewpoint of productivity.

[0012] The pH about the isoelectric point of the protein contained inthe water-insoluble vegetable fibers is normally within an acidic range(not higher than pH 6). For example, in the case of a residue obtainedby extracting fats and oils and protein from soy beans, i.e. “okara”, pH3 to 6 is preferable.

[0013] Further, when husks such as peels and the like are contained inthe water-insoluble vegetable fibers, the taste and flavor of thewater-soluble vegetable fibers obtained becomes inferior and, therefore,in the present invention, it is preferred to use water-insolublevegetable fibers from which husks-such as peels and the like areremoved. When the water-insoluble vegetable fibers are obtained from oilseeds, green flavor and the like of the resulting water-solublevegetable fibers can be reduced by using water-insoluble vegetablefibers from which husks and the like are removed. For example, in thecase of “okara” containing soybean protein, it is preferred to use“okara” obtained from dehusked soybeans.

[0014] “Okara” to be used in the present invention is a residue obtainedby adding water to defatted soybeans from which its oil fraction hasbeen extracted and removed, forming a slurry which contains okara and awater-soluble fraction by mixing the resultant mixture, e.g., withstirring and removing the water-soluble fraction, e.g., withcentrifugation.

[0015] When the water-soluble fraction is subjected to isoelectricprecipitation, e.g., by addition of an acid, it can be fractionated intosoybean protein and whey. Whey contains carbohydrates containingoligosaccharides and proteins such as soybean albumin and the like.

[0016] “Okara” contains water-insoluble fibers and soybean proteinswhich remain without extraction. Normally, “okara” contains about 40 to65% by weight of edible fibers based on the dry solids thereof.Suitably, “okara” contains 10 to 40% by weight, preferably 10 to 20% byweight of proteins based on the dry solids thereof.

[0017] In the present invention, the reason why the water-insolublevegetable fibers containing protein are degraded under acidic conditionsat about the isoelectric point of protein is that the vegetable fibersare excessively degraded under considerably stronger acidic conditionsthan those at the isoelectric point of protein, for example, in the caseof the degradation of “okara” containing soybean protein as describedabove under strong acidic conditions of pH 2 or lower, which results indeterioration of functions as the vegetable fibers. Further, protein isalso degraded together with the vegetable fibers and dissolved and,thereby, when the fibers are used for drinks and the like, clouding ofliquid is caused by neutralization. Furthermore, sufficientneutralization is required because of low pH and, therefore, the amountof a salt formed by neutralization increases, which requires anadditional desalting step.

[0018] On the other hand, when water-insoluble vegetable fiberscontaining protein are degraded at a considerably higher pH than theisoelectric point of protein such as under neutral or alkalineconditions, for example, when “okara” containing soybean protein asdescribed above is degraded under alkali conditions, i.e., at a pHhigher than 7, protein is degraded and dissolved together with thevegetable fibers and, therefore, clouding of liquid is caused, orbrowning tends to be caused by reaction of sugars with amino acidsproduced by degradation.

[0019] The reason why the water-insoluble vegetable fibers containingprotein are degraded at a temperature of not higher than 130° C. isthat, when a temperature rises to higher than 130° C., sugars producedby degradation (reducing sugars) react with amino acid to cause browningor an intense bad odor is caused. The temperature at which thewater-insoluble vegetable fibers containing protein are degraded can be130° C. or lower. In order to carry out the degradation efficiently, thetemperature should be higher than room temperature, preferably 80° C. orhigher, more preferably 100° C. or higher.

[0020] Preferably, the water-soluble vegetable fibers produced byfractionating water-insoluble vegetable fibers at a high temperatureunder acidic conditions are further treated with activated charcoal toremove hydrophobic materials and low molecular weight materials and,thereby, the purity of the water-soluble vegetable fibers can be furtherimproved.

[0021] The water-soluble vegetable fibers thus obtained containwater-soluble hemicellulose, for example, the water-soluble soybeanfibers obtained from the residue of soybeans, “okara”, are composed ofrhamnose, fucose, arabinose, xylose, galactose, glucose and uronic acidas the constituent saccharide component, and have an average molecularweight of from 50,000 to 1,000,000, preferably from 100,000 to 400,000.

[0022] In the present invention, the average molecular weight ofsaccharides is determined by measuring the viscosity in 0.1M sodiumnitrate solution according to intrinsic viscosity using standardpullulan (manufactured by Hayashibara Seibutsu Kagaku Kenkyusho) as thestandard substance. The proportion of saccharides are determined by thefollowing analytical methods.

[0023] Uronic acid is determined by Blumen-Krantz method. Neutralsaccharides are determined by alditol-acetate method.

[0024] The water-soluble vegetable fibers of the present invention thusobtained are superior in adhesive, film-forming properties, tensileproperties of film, thickening properties (particularly, they havethickening properties within an alkaline range but, the viscosity isdecreased under acidic conditions) and the like.

[0025] Hereinafter, transparent biodegradable films, paste, chewing gumand low calorie-food-prepared by using the water-soluble vegetablefibers of the present invention obtained from the water-insolublevegetable fibers are illustrated.

[0026] The film of the present invention is a biodegradable film whichhas sufficient strength even in the form of a thin film, can besubjected to heat-sealing and is produced at a low production cost.

[0027] The biodegradable film can be prepared from the water-solublevegetable fibers by using a known film forming method. For example, thewater-soluble vegetable fibers can be extended on a plate or resinmembrane in a suitable thickness and then they are dried to prepare thebiodegradable film.

[0028] Further, in order to improve the properties of the biodegradablefilm, it is possible to add additives such as plasticizers, surfactantsand the like. When such additives are used, it is preferred to selectthe additives so that they do not adversely affect the edibility of theabove biodegradable film.

[0029] The paste of the present invention is an adhesive whose maincomponent is the water-soluble vegetable fibers, particularly, the pasteof the present invention is a remoistening adhesive.

[0030] When the protein content of the water-soluble vegetable fibersused is lower (normally, less than 10% by weight based on the drysolids), adhesion becomes stronger. Preferably, the protein content isnot higher than 8% by weight, more preferably, not higher than 5% byweight.

[0031] The chewing gum of the present invention is that containing thewater-soluble vegetable fibers.

[0032] In general, a chewing gum is composed of a gum base (normally,from 15 to 30% by weight), a sweetener (sugar, glucose, malt syrup andthe like), and flavors and nutriments (normally, from 0.2 to 2% byweight). The gum base is composed of a natural resin, vinyl acetateresin, an ester gum, a synthetic gum, a natural wax, an emulsifyingagent, calcium carbonate and the like.

[0033] Preferably, the content of the water-soluble vegetable fibers inthe chewing gum of the present invention is from 1 to −40 parts byweight, preferably 2 to 30 parts by weight per 100 parts by weight of agum base. In the case of a chewing gum such as flavored gum, bubble gumor the like, normally, the content of the water-soluble vegetable fibersof about from 0.2 to 10% by weight is preferred. In the case of achewing gum containing less sweeteners, since as the content ofsaccharides is decreased, the amount of the water-soluble vegetablefibers is larger than this. When the content of the water-solublevegetable fibers becomes too large, visco-elasticity is increased andthe chewing gum becomes hard upon chewing. On the other hand, when thecontent becomes too small, the effect of the present invention is lost.

[0034] Since the dissolution rate in the mouth at a suitable content ofthe water-soluble vegetable fibers is slower than that o£ pullulan,superior durability of pleasant chewing properties and lasting of flavorcan be obtained.

[0035] The low calorie food products of the present invention are foodproducts composed of, as main raw materials, oils and fats andcarbohydrate wherein a part of the raw materials is replaced with thewater-soluble vegetable fibers to decrease the calories.

EXAMPLES

[0036] The following examples further illustrate the present inventionin detail.

Example 1

[0037] Process for Preparing Water-Soluble Vegetable Fibers

[0038] In this example, raw “okara” obtained during the production ofisolated soybean protein from defatted soybeans was used aswater-insoluble vegetable fibers containing protein. The raw “okara”contained about 80% by weight of water and its solids componentcontained about 65% by weight of vegetable fibers and about 20% byweight of crude protein. The isoelectric point of the protein was aboutpH 4.5.

[0039] After addition of twice the amount of water was added to this raw“okara”, 36% hydrochloric acid was added to the mixture to adjust to pH3 to 6. Then, the mixture was degraded by heating at a temperature ofnot higher than 130° C. In the “okara” thus degraded, thewater-insoluble vegetable fibers were degraded into water-solublevegetable fibers. On the other hand, most of protein contained in theraw “okara” remained in an aggregated state without degradation.

[0040] The resulting degraded material was centrifuged at 8,000 rpm for30 minutes and the precipitated fraction containing the aggregatedprotein was removed to obtain a supernatant wherein water-solublevegetable fibers were dissolved.

[0041] The supernatant contained a large amount of the water-solublefibers obtained by degrading the water-insoluble fibers. On the otherhand, the amount of protein which was degraded and dissolved wasdecreased and, therefore, browning of the solution and clouding of theliquid upon neutralization were not observed.

[0042] Then, experiments were carried out by varying the amount ofaddition of 36% hydrochloric acid or 50% sodium hydroxide to the mixtureof raw “okara”, which was diluted with the addition of twice the amountof water as described above, to change the pH of a mixture, or thetemperature of heat degradation of a mixture whose pH was adjusted toproduce water-soluble vegetable fibers. Products-obtained under theconditions of the above example were compared with those outside of theconditions of the above example.

[0043] (Experiments No. 1 to 11)

[0044] In these experiments, samples in the range of pH 1 to 14 wereprepared by, as shown in Table 1, appropriately varying the amount ofaddition of 36% hydrochloric acid or 50% sodium hydroxide to the mixtureof raw “okara”, which was diluted with the addition of twice the amountof water as described above.

[0045] After adjusting the pH, the mixture was degraded by heating at120° C. for 1.5 hours, a precipitated fraction was removed bycentrifugation as described above to obtain a supernatant.

[0046] If necessary, the resulting supernatant was neutralized and thecolor and flavor were evaluated. The results are shown in Table 1.

[0047] The evaluation of the color of the supernatant in Table 1 isexpressed by the following criteria: “D” is dark brown to black, “C” isbrown, “B” is pale brown, and “A” is colorless. TABLE 1 ExperimentEvaluation No. pH of Color Evaluation of flavor 1 1 C scorched and saltyflavor 2 2 C scorched and salty flavor 3 3 B good, some salty flavor 4 4A good 5 5 A good 6 6 A good 7 7 B good, but some strange flavor 8 8 Bstrange flavor 9 10 B strange and salty flavor 10 12 C strange and saltyflavor 11 14 C strange and salty flavor

[0048] With regard to Experiment No. 1 to 6, the yield of the.water-soluble fraction in the supernatant, the protein content in thewater-soluble fraction (% by weight), and the turbidity (OD 610 nm) ofthe aqueous solution wherein the content of the water-soluble fractionwas adjusted to 4% by weight after neutralization were measured.

[0049] These results are shown in Table 2. TABLE 2 Experiment No. YieldProtein content Turbidity 1 78.5 20.5 2.729 2 77.8 16.0 1.396 3 76.210.5 0.085 4 72.9 6.2 0.068 5 62.8 5.2 0.090 6 61.7 7.2 0.161

[0050] (Experiments No. 12 to 22)

[0051] In these experiments, twice the amount of water was also added toraw “okara”. In to the same manner as that described in the aboveExperiments No. 1 to 11, the amount of addition of 36% hydrochloric acidor 50% sodium hydroxide was varied as shown in Table 3 to preparesamples in the range of pH 1 to 14.

[0052] Then, after the mixtures were degraded by heating at 130° C. for1.5 hours, the precipitated fraction was removed by centrifugation asdescribed above to obtain a supernatant.

[0053] If necessary, the resulting supernatant was neutralized and thenthe color and flavor were evaluated as described above. The results areshown in Table 3. TABLE 3 Experiment Evaluation No. pH of ColorEvaluation of flavor 12 1 C scorched and salty flavor 13 2 C scorchedand salty flavor 14 3 B good, some salty flavor 15 4 A good 16 5 A good17 6 A good 18 7 B good, but some strange flavor 19 8 B strange flavor20 10 C strange and salty flavor 21 12 C strange and salty flavor 22 14C strange and salty flavor

[0054] (Experiments No. 23 to 44)

[0055] In these experiments, twice the amount of water was also added toraw “okara”. In the same manner as that described above, the amount ofaddition of 36% hydrochloric acid or 50% sodium hydroxide was varied toadjust the pH in the range of 1 to 14.

[0056] Then, in Experiments No. 23 to 33, the mixture was degraded byheating at 140° C. for 1.5 hours, and, in Experiments No. 34 to 44, themixture was degraded by heating at 150° C. for 1.5 hours.

[0057] Then, the precipitated fraction was removed by centrifugation asdescribed above to obtain a supernatant. If necessary, the supernatantwas neutralized and the color and flavor were evaluated as describedabove. The results are shown in Tables 4 and 5. TABLE 4 ExperimentEvaluation No. pH of Color Evaluation of flavor 23 1 D scorched andsalty flavor 24 2 D scorched and salty flavor 25 3 C scorched and somesalty flavor 26 4 C scorched flavor 27 5 B scorched flavor 28 6 Bscorched flavor 29 7 C scorched flavor 30 8 C scorched flavor 31 10 Cscorched and salty flavor 32 12 D scorched and salty flavor 33 14 Dscorched and salty flavor

[0058] TABLE 5 Experiment Evaluation No. PH of Color Evaluation offlavor 34 1 D scorched and salty flavor 35 2 D scorched and salty flavor36 3 D scorched and some salty flavor 37 4 D scorched flavor 38 5 Dscorched flavor 39 6 D scorched flavor 40 7 D scorched flavor 41 8 Dscorched flavor 42 10 D scorched and salty flavor 43 12 D scorched andsalty flavor 44 14 D scorched and salty flavor

[0059] As seen from the results in each experiment as shown above, theproducts of the experiments wherein the mixture of raw “okara” and twicethe amount of water was adjusted to pH 3 to 6, and degraded by heatingat a temperature of 130° C. or lower according to the conditions of theabove example (Experiments No. 3 to 6 and 14 to 18) have a lower contentof protein dissolved, a lower turbidity of the resulting liquid andlesser browning in comparison with the products of the other experimentscarried out under the conditions outside of the above example. Further,the products of the former experiments have superior flavor.

Example 2

[0060] In this example, raw “okara” obtained during the production ofisolated soybean protein from defatted soybeans was used aswater-insoluble vegetable fibers. This raw “okara” contained 80% byweight of water and its solids component contained about 65% by weightof vegetable fibers and about 20% by weight of crude protein.

[0061] Water was added to the raw “okara” to adjust the dry solidscontent to about 5% by weight and the mixture was homogenized twice at200 kg/cm² with a high pressure homogenizer (“Sub-Micron-dis-perser”manufactured by MANTON-GAULIN Co.).

[0062] Then, an equal amount of water was added to the homogenizedmixture and the mixture was stirred. To the mixture was added a protease(strength: 240 pu/mg) derived from Aspergillus oryzae so that the E/Sratio became 1/100 to degrade protein in the raw “okara” at 50° C. for 3hours. The strength of the protease was determined according to theHagiwara-Anson method.

[0063] After degradation of protein, the mixture was centrifuged at8,000 rpm for 30 minutes, the solubilized protein was removed and waterwas added to the remaining precipitated fraction to adjust the solidscontent to about 4% by weight. To the mixture was added 36% hydrochloricacid to adjust to pH 3 and degradation was carried out at 100° C. over 6hours to degrade water-insoluble vegetable fibers to water-solublevegetable fibers.

[0064] To the resulting degraded material was added 10% sodium hydroxidesolution to neutralize to pH 7.0 and the mixture was centrifuged at8,000 rpm for 30 minutes to obtain a water-soluble fraction containing alarge amount of water-soluble vegetable fibers. After the water-solublefraction was concentrated until the solids content became about 5% byweight, the residue was extended thinly on a synthetic resin film, driedto form a film and released from the synthetic resin film. Thebiodegradable film thus obtained increased in transparency and it was analmost transparent and strong film. Further, the film was dissolvedentirely in water without dispersion and was heat-sealable.

Example 3

[0065] In this example, 99% ethanol was added to a water-solublefraction containing a large amount of water-soluble vegetablefibers-obtained by centrifugation as described in above Example 2 sothat an 80% ethanol solution was obtained to precipitate a highmolecular weight fraction of the water-soluble vegetable fibers in thewater soluble fraction.

[0066] After the precipitated high molecular weight fraction was driedin hot air, water was added to this so that a 20% aqueous solution wasobtained. In the same manner as that described in the above Example 2,the solution was extended thinly on a synthetic resin film, dried toform a film, and released from the synthetic resin film.

[0067] The biodegradable film thus obtained was, as described in theabove Example 2, an almost transparent and strong film and was dissolvedentirely in water without dispersion. The film was heat-sealable andmaintained transparency for a prolonged period.

Example 4

[0068] In this example, after twice the amount of water was added to theabove raw “okara”, 36% hydrochloric acid was added to the mixture toadjust to pH 2.5 and the mixture was degraded at 100° C. for 1.5 hours.

[0069] Then, the degraded material was treated by a homogenizer. By thetreatment of the degraded material with a homogenizer in this way, asmooth paste was obtained.

[0070] After addition of glycerin and sorbitol (each 1.0%) to thedegraded material in the form of a smooth paste as plasticizers, thepaste was cast by a casting method so that the thickness at castingbecame 1.0 mm, and dried to obtain a biodegradable film having 0.1 mm inthickness.

[0071] The resulting biodegradable film was a transparent, strong andsmooth film, and was heat-sealable.

Example 5

[0072] In this example, as described in the above Example 4, after twicethe amount of water was added to raw “okara”, 36% hydrochloric acid wasadded to adjust the pH. In this example, the pH was adjusted to 4.5,i.e., about the isoelectric point of soybean protein contained in theraw “okara”, and the mixture was degraded at 120° C. for 1.5 hours. Whenthe raw “okara” was degraded at pH 4.5, i.e., about the isoelectricpoint of soybean protein in this way, water-insoluble vegetable fibersin the raw “okara” were suitably degraded to form water-solublevegetable fibers. On the other hand, soybean protein contained in theraw “okara” was aggregated to prevent dissolution of protein in anaqueous solution wherein the water-soluble vegetable fibers weredissolved. The resulting degraded material was centrifuged at 8,000 rpmfor 30 minutes as described the above Example 2 to separate awater-soluble fraction containing a large amount of water-solublevegetable fibers and this fraction was concentrated until the solidscontent became about 5% by weight.

[0073] Then, according to the same manner as that described in the aboveExample 4, a film was formed from the concentrate.

[0074] The biodegradable film thus obtained was transparent and had alow protein content. It was heat-sealable.

Example 6

[0075] Production Process

[0076] Twice the amount (by weight) of water was added to the raw“okara” obtained during the production of isolated soybean protein andthe pH was adjusted to 4.5 with hydrochloric acid. The mixture wasdegraded at 120° C. for 1.5 hours, cooled, and centrifuged (10,000 g for30 minutes) to separate a supernatant and precipitate part. Theprecipitate part was washed with an equal weight of water, andcentrifuged to obtain a supernatant. The latter supernatant was combinedwith the above supernatant and the mixture was subjected to an activatedcharcoal column treatment. The resulting liquid was dried to obtainwater soluble-vegetable fibers (A).

[0077] Further, the water-soluble-vegetable fibers were dissolved in0.5% saline solution and reprecipitation was repeated three times sothat the ethanol concentration became 50%. The mixture was desalted byusing an ion exchange resin (“Amberlite IR-120B”, manufactured byOrgano) to obtain water-soluble vegetable fibers (B).

[0078] On the other hand, in the same manner, water-soluble vegetablefibers (C) were obtained except that the activated charcoal columntreatment was omitted.

[0079] The results are shown in Table 6. TABLE 6 Composition (%)Component A B C Water 5.71 7.75 5.10 Crude protein 1.93 1.03 5.43 Crudeash content 5.29 0.22 5.30 Polysaccharides 37.07 91.00 84.17 Averagemolecular 178,000 207,000 114,000 weight

[0080] Pigment component, hydrophobic component and low molecular weightcomponent were removed by the activated charcoal treatment.

[0081] The water soluble vegetable fibers of (A), (B) and (C) wereanalyzed for the saccharide composition. Uronic acid was measured byBlumen-Krantz method, and neutral saccharide was measuredalditol-acetate method.

[0082] The results are shown in Table 7. TABLE 7 Saccharide Composition(% by weight) Kind of Saccharides A B C Uronic acid 20.4 16.9 19.4Rhamnose 1.6 2.7 2.1 Fucose 2.7 5.2 3.9 Arabinose 19.9 19.2 23.1 Xylose6.4 8.4 5.8 Galactose 47.3 40.8 43.4 Glucose 1.8 0.9 2.3

[0083] The water-soluble vegetable fibers were tested for adhesionstrength by using a “zelkova tree (water content: 8.1%, specificgravity: 0.53 g/cm²)” according to JIS K6848-1987 and K6851-1976.Namely, the water-soluble vegetable fibers were dissolved in water toobtain a 20% solution, which was applied to a piece of a zelkova tree inan amount of 1008/m² and bonded to another piece of a zelkova treewithout heat pressing. After drying at 20° C. for 48 hours under RH of60%, the tensile shear strength was measured.

[0084] The results are shown in Table 8 TABLE 8 Tensile Shear StrengthAdhesion strength (kgf/cm²) A 56.4 B 85.0 C 44.1 Pullulan*¹ 40.5 Gumarabic*² 30.7

[0085] It was found that the tensile strength of the water-solublevegetable fibers obtained in Example 6 was strong.

[0086] Further, it was found that, when the purity of water-solublevegetable fibers was higher, the tensile shear strength became stronger.

Example 7

[0087] The water-soluble vegetable fibers obtained in the same manner asthat described in Example 6, fibers (A), were mixed with dextrin(manufactured by Sigma Co.) in the proportion shown in Table 9, and theadhesion strength was measured as described in Example 6. The resultsare shown in Table 9. TABLE 9 Adhesion strength (kgf/cm²) Dextrin (A)Adhesion Strength 100 0 19.6 80 20 36.2 50 50 50.0 20 80 54.2 0 100 58.2

[0088] It is possible to increase or control the adhesion strength ofdextrin by using a paste such as dextrin or the like together with thewater-soluble vegetable fibers.

Example 8

[0089] To 300 g of a commercially available vegetable fibers (“SELPHA”manufactured by Nippon Shokuhin Kakou, fibers obtained by removal ofstarch, protein, lipid and the like from hull of corn) was added 2700liters of water and the mixture was autoclaved (120° C. for 60 minutes)to degrade the fibers by heating. The degraded material was centrifuged(5,000 g for 10 minutes) to obtain a supernatant, to which ethanol wasadded so that the ethanol concentration became 60%. The operation forrecovering the precipitate fraction was repeated once and the combinedfraction was dried to obtain 111 g of water-soluble vegetable fibers.The fibers were analyzed as described above. The results are shown inTable 10. TABLE 10 Moisture content 8.70% Crude protein 0.36% Crude ashcontent 1.12% Polysaccharides 89.82%

[0090] The polysaccharide composition was analyzed as described above.The results are shown in Table 11. TABLE 11 Uronic acid 4.9% Ara 35.9%Xyl 45.7% Gal 6.1% Glc 7.4%

[0091] The average molecular weight and adhesion strength determined asdescribed above were 178,000 and 31.9 kgf/cm², respectively.

Example 9

[0092] When 5 parts by weight of water-soluble vegetable fibers obtainedas described in Example 6, fibers (A), were added to water-glass having70% moisture content, the adhesion speed was about twice faster than.that of water-glass alone.

Example 10

[0093] Vinyl acetate resin (340 parts by weight), natural chicle (330parts by weight) and polyisobutylene (200 parts by weight) were placedin a kneader and the mixture was melt-kneaded at 120° C. Then, glycerinaliphatic acid ester (30 parts by weight) was added and the mixture wasfurther kneaded. Talc (powder, 100 parts by weight) was added and themixture was kneaded to obtain a gum base.

[0094] Then, to the chewing gum kneader maintained at 60° C. was added amixture of the above gum base (25 parts by weight), the water-solublevegetable fibers (5 parts by weight) obtained as described in Example 6,fibers (A), water (5 parts by weight) and instant coffee (1 part byweight) and the mixture was kneaded. Then, powdered sugar (55 parts byweight), glucose (8 parts by weight) and flavor (1 part by weight) wereadded and the mixture was kneaded.

[0095] A sheet of chewing gum 5 cm in thickness was extruded with anextruder and rolled to 2 cm in thickness with a calendered roller.

Example 11

[0096] In the same manner as that described in Example 10, a chewing gumwas obtained except that the water-soluble soybean vegetable fibersobtained as described in Example 6 (C) was used instead of thewater-soluble soybean vegetable fibers (A).

Example 12

[0097] In the same manner as that described in Example 10, a chewing gumwas obtained except that the water-soluble soybean vegetable fibersderived hull of corn as described in Example 8 was used instead of thewater soluble-soybean vegetable fibers (A).

Comparative Example 1

[0098] In the same manner as that described in Example 10, a chewing gumwas obtained except that malt syrup (6.7 parts by weight) and water (3.3parts by weight) were used instead of the water-soluble soybeanvegetable fibers (A).

Comparative Example 2

[0099] In the same manner as that described in Example 10, a chewing gumwas obtained except that pullulan (manufactured by Hayashibara SeibutsuKagaku Kenkyusho) was used instead of the water-soluble soybeanvegetable fibers (A).

Comparative Example 3

[0100] In the same manner as that described in Example 10, a chewing gumwas obtained except that gum arabic (manufactured Kishida Kagaku) wasused instead of the water-soluble soybean vegetable fibers (A).

[0101] Experiment 1

[0102] The chewing gums obtained in the above examples and comparativeexamples were evaluated organoleptically by 30 panelists after storingat 20° C. under relative humidity (RH) 40% for 1 week.

[0103] The results are shown in Table 12 TABLE 12 Hardness at Lasting ofSample initial chewing taste Flavor Example 10 8.0 8.1 8.2 Example 118.1 8.0 7.2 Example 12 7.6 7.0 7.4 Comparative 8.0 6.4 7.8 Example 1Comparative 7.0 6.2 7.1 Example 2 Comparative 6.8 6.3 6.4 Example 3

[0104] The evaluation was carried out by scoring.

[0105] Score 10 represents the best properties and the larger scoreshows better properties. As seen from this experiment, it has been foundthat the chewing gum using the water-soluble vegetable fibers was softat initial chewing, and has good lasting of taste.

[0106] Experiment 2

[0107] The chewing gums obtained in the above examples and comparativeexamples were tested for the increase in water content after storing at40° C. under relative humidity (RH) 80% for 1 week.

[0108] The increase in water content was calculated from the followingformula.

Increase in water content (Δ %)=Water content after storing (%)−Initialwater content (%)

[0109] The results are shown in Table 13. TABLE 13 Sample Increased inwater content (Δ %) Example 10 1.0 Example 11 1.2 Example 12 2.1Comparative Example 1 3.4 Comparative Example 2 1.9 Comparative Example3 2.0

[0110] As seen from this examination, the chewing gum using thewater-soluble hemicellulose has good properties with less hygroscopicityin spite of being soft at initial chewing.

Example 13

[0111] Low Calorie Chocolate

[0112] According to the oxygen weight method (Prosky method), TDF (totaldietary fiber) of the water-soluble soybean vegetable fibers (A) wasmeasured. It was 70.6%. Namely, the water-soluble fibers were low incalories. Then, according to a conventional method, chocolate of thefollowing formulation was produced by using the low caloriewater-soluble fibers. Formulation (% by weight) Raw material Presentinvention Control Cacao mass 8.0 8.0 Cocoa butter 7.0 7.0 Lactose 0 7.0Water-soluble fibers 10.0 0 Powdered sugar 47.0 50.0 Cocoa butter 28.028.0 Lecithin 0.3 0.3

[0113] When the chocolate of the present invention was evaluatedorganoleptically, no substantial difference from the control chocolatewas found.

Example 14

[0114] Low Calorie Cookie

[0115] By using the water-soluble soybean vegetable fibers (A) obtainedas described in Example 6, cookies were prepared with the followingformulation according to a conventional method. Formulation (% byweight) Raw material Present invention Control Margarine 26.1 26.1 Whitesugar 15.7 15.7 Whole egg 5.2 5.2 Salt 0.26 0.26 Sodium bicarbonate 0.260.26 Ammonium carbonate 0.32 0.32 Low gluten content 39.1 52.2 flourWater-soluble fiber 13.0 0

[0116] When the cookie of the present invention was evaluatedorganoleptically, no substantial difference from the control product wasfound.

EFFECT OF THE INVENTION

[0117] As described hereinabove, according to the present invention, itbecomes possible to prepare water-soluble vegetable fibers fromwater-insoluble vegetable fibers in a high yield.

[0118] It also becomes possible to obtain a transparent biodegradablefilm having high tensile strength and low impurity by using thewater-soluble vegetable fibers thus obtained.

[0119] Further, it becomes possible to obtain a paste, particularly, aremoistening adhesive having strong adhesion strength. In the paste ofthe present invention, adhesion strength can be further improved byesterification or etherification and water resistance can be provided bycrosslinking or using together with a crosslinking agent. Furthermore,the paste of the present invention can be used together with anotheradhesive to increase adhesion strength or improve adhesion dependingupon the particular kind of adhesives.

[0120] Furthermore, it becomes possible to obtain a chewing gums havingsuperior properties such as lasting of pleasant chewing properties andlasting of flavor. Namely, it becomes possible to obtain chewing gums,candies, soft chewing gums, chewing gum confectionery, bubble gums andthe like containing water-soluble hemicellulose.

[0121] In addition, it becomes possible to obtain low calorie foodproducts by replacing a part of the protein and carbohydrates with thewater-soluble vegetable fibers of the present invention.

18. (New) A chewing gum comprising a biodegradable film obtained bysubjecting water-soluble vegetable fibers to film formation, wherein theamount of the water-soluble vegetable fibers is from 1 to 40 parts byweight per hundred parts by weight of a gum base.
 19. (New) The chewinggum according to claim 18 wherein the amount of the water-solublevegetable fibers is 2 to 30 parts by weight per hundred parts by weightof a gum base.
 20. (New) A low calorie food product which comprises asmain components, fats, oils and carbohydrates, and in which the caloriecontent is reduced by replacing a part of the main components withwater-soluble vegetable fibers.
 21. (New) A paste comprising, as a maincomponent, water-soluble hemicellulose having an average molecularweight of 50,000 to 1,000,000, which is obtained by degrading okaraunder acidic conditions at about the isoelectric condition of proteincontained therein and at a temperature of 80 to 130° C.
 22. (New) Achewing gum comprising water-soluble hemicellulose having an averagemolecular weight of 50,000 to 1,000,000, which is obtained by degradingokara under acidic conditions at about the isoelectric condition ofprotein contained therein and at a temperature of 80 to 130° C. 23.(New) A low calorie food product comprising water-soluble hemicellulosehaving an average molecular weight of 50,000 to 1,000,000, which isobtained by degrading okara under acidic conditions at about theisoelectric condition of protein contained therein and at a temperatureof 80 to 130° C.